1. Field of the Invention
The present invention relates to a random number generation device which generates a random number on the basis of a physical phenomenon.
2. Related Art
As the information communication technique advances and spreads, demands for high quality random numbers are becoming strong. Strength of information security depends upon the random number which becomes the source of prediction difficulty. In the field of scientific technical calculation as well, high quality random numbers are needed for more accurate calculation.
A typically used random number is an arithmetic pseudo random number which is generated through a certain algorithm. A circuit for generating this random number can be fabricated simply. Though, if the initial value (seed) is constant, an output random number always becomes constant. In addition, there is a problem that the output random number has a constant repetition period determined by the circuit configuration.
On the other hand, there is a physical random number generated by utilizing a physical fluctuation phenomenon unlike the arithmetic random number. In the physical random number, the output random number does not depend upon the initial value and a random number series having no repetition period can be obtained, by utilizing the physical fluctuation. An example of a random number generation device which generates such a physical random number is disclosed in, for example, JP-A 2006-189946 (KOKAI).
In the random number generation device disclosed in JP-A 2006-189946 (KOKAI), a high quality random number can be generated by utilizing a noise source which generates noise intentionally made large. In the random number generation device, however, a comparator is used to make random numbers from the noise generated by noise source. There is a problem that the comparator consumes a large amount of power.